Reversing decades of American foreign policy, President Donald Trump on Wednesday signed a proclamation recognizing Jerusalem as Israel’s capital and directing the State Department to start planning to move the U.S. embassy to the city. The embassy is currently in Tel Aviv.

“I have consistently spoken out against any unilateral measures that would jeopardize the prospect of peace for Israelis and Palestinians,” Guterres said Wednesday following Trump’s announcement.

A Security Council resolution in December said the body would “not recognize any changes to the 4 June 1967 lines, including with regard to Jerusalem, other than those agreed by the parties through negotiations.” The United States abstained from voting on that resolution, declining to use its veto power on the council and allowing the resolution to pass.